The goal of this research and training program is for the applicant to gain the tools necessary to become a leader in health services research and health care policy of homeless persons. Building on her training in primary care internal medicine and clinical epidemiology, the applicant proposes to develop additional skills through interaction with a multi- disciplinary sponsorship team 2) tutorials and coursework designed to expand her theoretical and methodological knowledge and skills and 3) a series of focused, supervised research projects. Prior research on the homeless has focused on individual characteristics of homeless persons; this research program focuses on the role that community factors play in the health care utilization and outcomes of the homeless. The proposed projects investigate the association between housing, case management and general homeless services and the health care utilization patterns and outcomes of the homeless, than examines the cost-effectiveness of these services. The specific aims are: 1) to examine the effects of different levels of community levels for the homeless (housing, health care, overall services) on hospitalization and emergency department rates of homeless adults and children 2) to examine the cost-effectiveness of case-management as a strategy for improving health outcomes among HIV infected homeless persons and 3) to examine health care utilization and public cost of a cohort of homeless persons under two different policy options: supportive housing and usual care. The University of California, San Francisco, with its extensive resources for health policy related research provides an excellent environment for the applicant to pursue research and training. The applicant's sponsor and mentorship team have vast experience in the relevant disciplines and will be critical in the applicant's development as an independent research with a focus on improving the health of the homeless.